ABSTRACT Support is requested for a Keystone Symposia conference entitled Neuropsychiatric and Neurodevelopmental Disorders: Harnessing Rare Variants for Diagnosis and Treatment organized by Drs. Jennifer G. Mulle, Audrey Thurm, Christa L. Martin and Carrie E. Bearden. The conference will be held in Boulder, Colorado from January 24-27, 2021. This is an unprecedented time in psychiatric genetics. There are now hundreds of rare genetic variants that are strongly associated with neuropsychiatric traits and psychiatric diseases. Many individual teams are making progress studying a given gene or genomic interval, and the time is right for knowledge transfer across teams. This conference is driven by three emerging concepts. First, the discovery of rare variants with large effects for neuropsychiatric disorders provides a new avenue for understanding the underlying mechanisms of more common disorders. Second, these rare variants are often associated with multiple neurodevelopmental or neuropsychiatric disorders, suggesting that there are common underlying biological pathways that confer susceptibility to disease; this finding simultaneously suggests that genetic and epigenetic modifiers play a key role in determining the phenotype of specific individuals. Third, large scale collaborative efforts and harmonized frameworks for data collection are starting to enable more fine-grained, quantitative and even longitudinal phenotyping of probands and relatives, allowing us to move beyond the relatively gross characterization of categorical Diagnostic and Statistical Manual of Mental Disorders (DSM) diagnoses. These new findings underscore the need for interaction between geneticists, neurobiologists and clinical scientists, and this meeting sets the stage for such cross-cutting collaborations.